1. Field of the Invention
The present invention generally relates to a touch panel and, more particularly to a transparent capacitive touch panel.
2. Description of the Prior Art
With the development in technologies, the electronic products having a touch panel as input such as personal digital assistants (PDA's), handsets, car navigating systems, tablet personal computers (PC's) have been widely used. The touch panel is provided on the screen for the user to use input information by a finger or a touch pen. There have been various kinds of touch panels developed. For example, the capacitive touch panel is based on the detection of the change of capacitance. Compared to the resistive touch panel based on direct touch, the capacitive touch panel exhibits higher transparency and longer lifetime.
FIG. 1A is a cross-sectional view of a conventional transparent capacitive touch panel, and FIG. 1B is an exploded view of the transparent capacitive touch panel in FIG. 1A. Please refer to FIG. 1A and FIG. 1B, the conventional transparent capacitive touch panel 100 comprises a dual-layer structure, which comprises a bottom transparent substrate 110, a top transparent substrate 120 and a transparent cover lens 130. A top indium-tin oxide layer 122 and a bottom indium-tin oxide layer 112 are respectively formed on the surfaces of the top transparent substrate 120 and the bottom transparent substrate 110. Two anti-reflection layers 132 are deposited respectively on the surfaces on both sides of the transparent cover lens 130.
Then, an optical adhesive 140 is used to bind the top transparent substrate 120 and the bottom transparent substrate 110 so that the optical adhesive 140 is sandwiched between the top indium-tin oxide layer 122 and the bottom indium-tin oxide layer 112 facing each other. The transparent cover lens 130 is bound with the top transparent substrate 120 by an optical adhesive 150 bind so as to complete the assembly of the transparent capacitive touch panel 100. The transparent cover lens 130 is used to protect the top transparent substrate 120 and the bottom transparent substrate 110.
Since the transparent capacitive touch panel 100 is too thick, another conventional structure is provided to reduce the thickness as shown in FIG. 2. More particularly, FIG. 2A is a cross-sectional view of another conventional transparent capacitive touch panel, and FIG. 2B is an exploded view of the transparent capacitive touch panel in FIG. 2A. Please refer to FIG. 2A and FIG. 2B, the conventional transparent capacitive touch panel 200 comprises a transparent substrate 210 and a transparent cover lens 220. A top indium-tin oxide layer 212 and a bottom indium-tin oxide layer 214 are successively formed respectively on the surfaces of the transparent substrate 210. Two anti-reflection layers 222 are deposited respectively on the surfaces on both sides of the transparent cover lens 220.
Then, an optical adhesive 230 is used to bind the transparent cover lens 220 and the transparent substrate 210 so as to complete the assembly of the transparent capacitive touch panel 200. Even though the transparent capacitive touch panel 200 is thinner, the manufacturing process is more complicated.
More particularly, the top indium-tin oxide layer 212 and the bottom top indium-tin oxide layer 214 are formed on the surface of the transparent substrate 210. After the indium-tin oxide layer 212 is formed, the transparent substrate 210 is turned up side down so that the indium-tin oxide layer 214 can be formed. However, this causes the top indium-tin oxide layer 212 to be harmed by contacting the platform or the robot arms and lower the manufacturing yield of the transparent capacitive touch panel 200.
FIG. 3A is a cross-sectional view of still another conventional transparent capacitive touch panel, and FIG. 3B is an exploded view of the transparent capacitive touch panel in FIG. 3A. Please refer to FIG. 3A and FIG. 3B, the conventional transparent capacitive touch panel 300 comprises a transparent substrate 310 and a transparent cover lens 320. A bottom indium-tin oxide layer 312, an insulating layer 314, a top indium-tin oxide layer 316 are successively formed on the surface of the transparent substrate 310. Two anti-reflection layers 322 are deposited respectively on the surfaces on both sides of the transparent cover lens 320.
Then, an optical adhesive 330 is used to bind the transparent cover lens 320 and the transparent substrate 310 so as to complete the assembly of the transparent capacitive touch panel 300. Even though the transparent capacitive touch panel 200 is thinner, the manufacturing process is more complicated.
However, there are still problems in manufacturing two indium-tin oxide layers on a single side of the transparent substrate 320.
More particularly, conventionally, the formation of the insulating layer 312 results in longer manufacturing time and cost of the transparent capacitive touch panel 300. Moreover, a contact window (not shown) has to be formed in the insulating layer 312 so that the top indium-tin oxide layer 316 is electrically connected to an integrated circuit (IC) (not shown) on the transparent substrate 310. The formation of the contact window leads to increased cost for preparing a mask. Therefore, the manufacturing cost and complexity of the transparent capacitive touch panel 300 is significantly increased.